A meteorite called Semarkona, weighing about 1.5 pounds that crashed in northern India in 1940 is now being investigated by researchers for signs of primordial magnetic fields.
Most other meteorites were altered in some way that would remove their original magnetization — maybe they were heated, or water flowed through them, or they experienced high pressure from impacts, Semarkona is one of the few meteorites we know of that avoided all of these things.
Roger Fu
Lead study author, Roger Fu, a planetary scientist at MIT in Cambridge, Massachusetts, says: “It’s a very primitive meteorite, which means that since it formed about 4.5 billion years ago, not much has happened to it, this means it preserves the properties it had when it first formed, helping shed light on that time.”
This meteorite is made up of mostly tiny round pellets known as chondrules, which formed droplets that quickly cooled in space. According to the study, the scientists focused on these chondrules that possessed iron-bearing minerals, known as dusty olivine crystals, and if they appeared to have a magnetic field present while they were cooling, then the magnetic properties of these crystals might have recorded the strength of the magnetic fields.
Researcher have been looking at meteorite samples since the 1960s in order to search for evidence of magnetic fields in the primordial solar system, but haven’t had much success. Fu says: “Most other meteorites were altered in some way that would remove their original magnetization — maybe they were heated, or water flowed through them, or they experienced high pressure from impacts, Semarkona is one of the few meteorites we know of that avoided all of these things.”
Analyzing the magnetic signature of these chondrules was not easy, but the scientists found that they were magnetized in a field of roughly 54 microtesla in strength, which is about as strong as the Earth’s magnetic field and up to 1000,000 times stronger than what exists in interstellar space today.
Astronomer Meredith Hughes from Wesleyan University in Middletown, Connecticut did not take part in the study, but says about it:
“This discovery tells us that magnetic fields were large enough to be important in the accretion process that helped form the solar system. We had guessed that, but we had no evidence of that until now”.
This archive content was originally published November 16, 2014 (www.betawired.com)